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By R. A. Pimentel

Many longwall operators experience difficulty complying with the federal regulation limiting average dust exposure. Others are currently in compliance, but the dust exposure limit keeps then from increasing their production. Spray water is a major means of dust control. Excess water can cause problems in the transportation system and the cleaning plant, and reduces the Btu value of the run of mine coal. Thus, the dust exposure reduction per unit of water sprayed must be maximized. This paper discusses underground tests recently completed as part of a Bureau of Mines research program to determine the effects of variations in spray water flow rate, pressure, proportioning and spray orientation on longwall shearers.

Jan 1, 1984

By A. B. Kinzel

ALTHOUGH vanadium is an important constituent of almost every brand of high-speed steel manufactured today, little is known as to its role in this series of alloys. The now standard 18 per cent tungsten and 4 per cent chromium constituents were the result of developments and improvements before 1903. In that year, vanadium was added to the steel by Dr. J. A. Mathews. This proved to be an outstanding con-tribution, so that the standard high-speed steel of today is generally referred to as the 18-4-1 type-18 per cent W, 4 per cent Cr and 1 per cent V. Various modifications have been attempted, since then, but with the exception of the introduction of cobalt, no striking improvements have occurred. Vanadium has been increased to 2 per cent in many of the common brands, and at least one brand contains 5 per cent V in addition to the usual tungsten and chromium. The carbon has been gradually increased so that it is not uncommon to find 0.80 per cent in the standard grade, although the carbon in the 5 per cent vanadium steel mentioned above is approximately 1 per cent, and even 1.2 per cent has been made experimentally. The role of vanadium has never been well understood, and although vanadium has been increased to 2.5 and even 5 per cent in certain high speed steels, it has not been generally established that the higher vanadium contents 'result in superior cutting properties. However, in all of the investigations, of which the writers are aware, the interrelation of the vanadium and carbon contents was not considered as a prime factor. The carbon content was held at 1.2 per cent or less-generally at the usual 0.65 to 0.75 per cent.

Jan 1, 1932

By Don Thompson

Canada’s oil sands are a controversial topic and virtually every newsmaker and layperson seems to have an opinion about this 179 billion barrel resource. The oil sands represent 97 per cent of Canada’s remaining oil reserves, but misinterpretation and misrepresentation of the facts are threatening development of a resource that generates significant employment and tax revenue for Canadians. Join Don Thompson, president of the Oil Sands Developers Group, as he dispels the top ten myths about Canada’s oil sands and presents an alternative perspective on an industry that can play a critical role in North America’s economic recovery.

Jan 1, 2010

By A. Gakwaya, K. Ba, M. Guillot, J. Levesque

"In the aerospace industry, parts requiring tight dimensional tolerances and high mechanical properties are often produced by forging. This forming process allows for an optimal use of the material and can produce high quality parts at a reasonable cost. Thanks to CAD techniques, it is now easier to predict flow profiles and in-process defects occurrence as well as wear of the forging dies. However, in order to determine the properties of the forged part with computer simulation methods, a good material constitutive law is a prerequisite. This paper presents a virtual manufacturing process modeling for the closed die forging of a workpiece performed with Abaqus. The hot closed die forging is a regular process applied to manufacture metallic components used in aerospace industry. In this forming process, the material flow and final properties depend on the microstructure evolution during the process that is why it is important to include the microstructure effects in the material model. Based on the stress-strain data measured experimentally, the material parameters of the standard (classical) Johnson-Cook constitutive model and of a modified Johnson-Cook constitutive law including the microstructure effects have been determined. The obtained simulation results are compared with the experimental results for validation.INTRODUCTIONDue to their good physical and mechanical properties such as ductility, fatigue strength, corrosion resistance and rupture, aluminium alloys are often used in the aeronautic and the automobile industries. In this work, we present the forging of an Al-Zn-Mg-Cu alloy, a high strength aerospace alloy recognized for his good combination of physical and mechanical properties. The forging process is simulated in Abaqus Explicit using both the standard Johnson-Cook law (Johnson & Cook, 1983; Hor, 2011; Lin et al., 2012), and its modified version as proposed by Andrade et al., (1994). The Johnson-Cook law offers the advantage of considering the coupled effect of the plastic strain, the plastic strain rate, the temperature of forging and the hardening effect. However, it is a phenomenological model which does not account for the effect of the microstructure evolution. In this work, a modified Johnson-Cook model implemented in a user subroutine is used. It includes the effect of the dynamic recrystallization phenomenon during the hot deformation. The dynamic recrystallization has a noticeable influence on the microstructure and on the properties of the material. The term dynamic means that the process starts and acts during the deformation and this is different from the static mechanism of recrystallization which occurs during an annealing and after cold or hot deformation. Since properties of the alloy used in this work are not readily available in the literature then characterization tests have been done at various temperatures and strain rates, in order to determine the thermomechanical properties and the material behavior during the process of hot forming, more precisely during the hot forging process."

Jan 1, 2016

By Christopher Mark

After the United States and Australia, South Africa has the largest. modern underground coal mining industry in the world. Historically, South Africa has been the cradle of many innovations in ground control, particularly in the area of pillar design. Today, South African mines are grappling with many of the same issues faced by their U.S. counterparts, including safety during pillar retreat operations, selecting the proper roof support, and maintaining long-term pillar stability. The author recently visited seven underground mines in the Mpumalanga, Free State, and KwaZulu-Natal provinces. Mining methods included longwall, room-and-pillar with continuous miners, and drill-and-blast. The mines represented a cross-section of geology and ground support practices. At each mine evaluations were made of the Coal Mine Roof Rating (CMRR), roof support practices, pillar design methods, and general ground control experience. The coal seams observed were generally thick (2-5 m), the depths of cover moderate (less than 200 m), and the roof rocks relatively strong (CMRR greater than 45). Unfortunately, the South African roof fall fatality rate is approximately three times greater than in U.S., perhaps in part because roof bolts seem to be more widely spaced in most South African mines. Roof bolting equipment was generally outdated, and the quality of bolt installation was a major concern. Pillar design, on the other hand, is quite advanced, and pillar failures are rare. Several novel partial pillaring techniques are employed, including "checkerboard" mining in which every other pillar is removed, 3-cut systems, and high-extraction mining where engineered final stumps are left by design. The paper also offers observations on ground control management techniques (including recently introduced Codes of Practice), the role of the mine inspectorate, and the status of the research community.

Jan 1, 1999

By Arthur C. Simmons

In common with all other producing areas of the United States, Pennsylvania enjoyed increased activity and prosperity during 1937 (Table I). Prices of crude oil were better than for any year since 1930, and the Bradford average was $2.599, compared with an average price of $2.60 in 1930. Production and drilling activities were increased over 1936, although drilling for oil represented almost entirely a program of secondary development in both the water-flood areas and the air-gas repressuring areas. Bradford Oil Field The Bradford oil field continued to produce the major portion of Pennsylvania oil; however, no changes occurred in oil-production methods during 1937. Practically all of the production in the Bradford field is by water-flooding and the total number of oil and water wells completed within the area increased from 3205 in 1936 to 4112 in 1937; an increase of approximately one-third over 1936 completions. The percentage of water wells is approximately one-half of the total completions, although any specific five-spot development will have a proportion of 55 to 60 per cent water wells and 40 to 45 per cent oil wells. Offsetti~ig and boundary oil wells probably will result in a division or percentage of 50 per cent oil and 50 per cent water wells. The quoted figures for well completions include the entire Bradford field, approximately 12 per cent of which is in Cattaraugus County, New York. It is possible to make a segregation of production, but it is not possible to segregate well completions. Production in the Pennsylvania end of the Bradford field in 1937 totaled 15,076,000 bbl., or a daily average of 41,300 bbl. compared with a daily average of 37,000 hbl. in 1936.

Jan 1, 1938

By Steven G. Jansto

Nearly one third of the globally produced structural flat and long structural products are in the 0.11 to 0.16% carbon range. By definition, numerous steelmakers globally define this approximate carbon range as peritectic in their melting grade family within their organization. The metallurgical consequence is the result of numerous global structural specifications which allow carbon to wide carbon ranges resulting in quality issues. For example, such specifications as ASTM A588 set no minimum carbon and a 0.15 to 0.19%C maximum depending on the specific grade designated within the specification. This peritectic region is specifically challenging in production compared to less than 0.10%C because of solidification issues and a higher propensity for slab or billet cracking during continuous casting. During hot rolling, rejects and/or deviates are increased as well. The relative steelmaking operational cost of production is compared between peritectic and non-peritectic carbon compositions for a given specification.

Aug 17, 2017

By W Mackinnon

Coal mining operations require the expenditure of appreciable start up and working capital in order to produce saleable coal for domestic or export markets. The competitive nature of the coal business restricts margins, and so it is imperative that downside risks, in terms of production outcomes, are minimised. The major risks identified for a coal mining operation, aside from sales volumes and coal price, are generally thought to be confined to the geology of the deposit and the mining process. However, the impact of product quality and yield can be very significant. If product coal is inferior to projections, then it will need to be sold at a discounted price and this can dramatically impact on margins. Equally, if yield is five to ten per cent less than planned, then this will have a huge effect on profitability. This paper will look at issues relating to in situ moisture and density, resource quality evaluation, modelling of washability and dilution, and simulation techniques, and how best practice approaches can be incorporated into mine planning and feasibility studies. Risks are best modelled and understood by adopting a detailed approach that is fully documented and auditable. This is particularly needed for multi-seam and multi-product operations. Once a well defined systematic approach is established the potential risks can be evaluated by testing different scenarios, carrying out sensitivity analyses, variability modelling and examining extreme operating conditions. These have been discussed in the paper, along with some related issues such as the cost of quick fixes and the value of spending a little more in the coal preparation area.

Jan 1, 2003

By F. Chachula, A. Molinaro

"Sulphide mineral flotation operations continuously strive for a balance between mineralogy, mineral liberation, circuit conditions and reagent solutions to maximize the production rate and recovery of payable metals. The Taseko Gibraltar copper – molybdenum mill operations underwent an extensive project focusing on the fundamentals to identify the effects of process conditions and mineral liberation to improve the bulk circuit copper – molybdenum recovery efficiencies in the bulk flotation circuits. This discussion will provide process data that demonstrates; 1) fundamental relationship between mineral liberation to recovery and grade, 2) flotation circuit condition testing and optimization, 3) reagent combinations resulting in efficient/economical mineral recovery, and 4) the development of a xanthate free reagent solution. The data presented and discussed will also touch on flotation parameters including pH, retention time, kinetics and the effect on bulk circuit recovery performance.INTRODUCTION Taseko's is the owner (75%) and operator of the Gibraltar copper-molybdenum mine, located in south-central British Columbia, the second largest open pit copper mine in Canada and the largest employer in the Cariboo region. Taseko restarted Gibraltar in 2004. From 2006 until 2012, the company invested ~$700 million to expand and modernize the operation which was originally scheduled for demolition when the company acquired it in 1999. In the spring of 2011, construction commenced for Gibraltar Development Plan 3 (GDP3). GDP3 included the construction of a standalone 30,000 ton per day concentrator, built adjacent to the existing 55,000 ton per day facility. The new design capacity of Gibraltar was designed to be 85,000 tons per day. An integral part of the project was a new molybdenum recovery facility. In addition to the new concentrator, the mining fleet was upgraded with a new mining shovel, production drill and ten haul trucks (Taseko, May 2015). In May of 2015, the Company completed an updated mine plan for Gibraltar featuring a 50% decrease in strip ratio. This new mine plan was a result of a detailed, six-month engineering study and forms the basis of an updated NI 43-101 compliant reserve (Taseko Announces Improved Economics At Its Gibraltar Copper Mine, 2015). The new mine plan took into account lower milling costs as a result of the modernized processing facilities (Taseko, May 2015)."

Jan 1, 2018

In the five years since Great Central Mines Limited (GCM) commenced exploration in the Jundee and Bronzewing areas of Western Australia's Yandal greenstone belt, the Company has been transformed from a junior explorer into Australia's fourth largest gold producer with annual production of approximately 440 000 ounces and mineral resources of seven million ounces of gold.The growth in resources has been driven by a high quality geoscientific approach, supported by a substantial budget for drilling and strong management commitment. In 1997, the Company expects to spend US$30 million on exploration in the Yandal greenstone belt.

Jan 1, 1997

By Robert C. Hickman

"INTRODUCTION The Big Four fault and the Sandy Creek fault, with several cross faults, traverse the Stalion-Curnel fluorspar prospect in a northeasterly direction. The Big Four mine, about three-quarters of a mile northeast of the prospect, is the only active mine in the immediate area.A resistivity survey was made of a portion of the prospect by the Division of Geophysical Exploration, Bureau of Mines, in May and June 1946. As a result of this survey, five holes were drilled by the Bureau of Mines during the period from October 8 to December 16, 1946. Two Longyear No. 12 Junior Straitline diamond drills were used for the work.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each project as soon as practicable after its conclusion. The Mining Division, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Division, Oliver C. Ralston, chief, analyzes samples and makes beneficiation tests.The project was under the supervision of Mitchell H. Kline, chief, Raleigh Branch, Mining Division."

Mar 1, 1948

By S. L. Chen

The Kumera Technology Center developed a unique type of steam dryer for drying copper concentrate in the mid 1990s. The dryer has been chosen in several copper smelter projects since 1999. To expand production capacities, the Norddeutsche Affinerie smelter, the Pirdop smelter of Cumerio, the Toyo smelter of Sumitomo Metal Mining and the Tamano smelter of Hibi Kyodo Smelting have carried out projects in which Kumera Steam Dryers were installed. The capacity of a single steam dryer varies from 70 t/h to 160 t/h. This article summarizes the latest operation results of the Kumera Steam Dryers in these smelters and introduces the progress of the ongoing projects in Yanggu Xiangguang Copper, Guixi smelter of Jiangxi Copper, Jinlong Copper, Boliden Harjavalta, and Onsan smelter of LS-Nikko Copper.

Jan 1, 2007

By Mah Alla D.

Previously existing heat-of-formation values for the oxides of vanadium were rudimentary. They were subject to uncertainties of 1 to 5 kilocalories per gram-atom of contained oxygen. This fact has been the only adverse influence on the accuracy of thermodynamic calculations involving these substances, as the requisite entropy and high-temperature heat-content data are known with reasonable accuracy. This report presents new heat-of-formation data for four oxides of vanadium (VO, V203, V02, and V205), obtained by combustion calorimetry. It is believed that the uncertainties have been reduced to 0.1 to 0.3 kilocalorie per gram-atom of contained oxygen. The new heat-of-formation data were combined with existing entropy and high-temperature heat-content values to obtain free energies of formation of the four oxides at temperatures up to 2,000° K.

Jan 1, 1961

By J Chan, T Baumgartl, A Plante, C Peltre, P D. Erskine

Mine soils are often organic matter and carbon poor due to disturbance, topsoil stockpiling and mixing with spoil. They present an opportunity to observe the accumulation of soil carbon arising from rehabilitation or ‘green carbon’ through organic matter inputs and may be considered for carbon credits. Soil carbon is known to improve multiple soil characteristics and is viewed as an indicator of soil health.When attempting to estimate soil carbon levels in the Australian coal mining regions, both coal and black carbon (BC) need to be quantified. Coalmine soils contain coal particles that are difficult to distinguish from organic matter using standard carbon analyses. BC, a material arising from the incomplete combustion of organic matter and fossil fuels, displays some similar characteristics to coal and is ubiquitous in Australian soils due to bushfires. The presence of coal and BC complicate the determination of green carbon levels in mine soils.A method to quantify coal and BC in mine soils from the Bowen Basin using thermal analysis and multivariate curve resolution is presented. By determining BC and coal contributions it is then possible to calculate green carbon levels in rehabilitated mine soils. Calculated green carbon levels are compared with bulk density as soil quality indicators.CITATION:Chan, J, Baumgartl, T, Erskine, P D, Peltre, C and Plante, A, 2014. Distinguishing carbon fractions in coalmine rehabilitated soils, in Proceedings Life-of-Mine 2014 , pp 491–498 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By Cláudia Lisiane Fanezi da Rocha

Softwares desenvolvidos para análise das propriedades mecânicas em máquinas de ensaio de tração facilitam o trabalho rotineiro de caracterização dos materiais. No entanto, estes aplicativos não apresentam informações importantes como cálculos da incerteza de medição, cabendo uma análise da confiabilidade dos resultados obtidos por esses programas. O presente trabalho se propõe a comparar os valores dos limites de escoamento, de resistência, do módulo de elasticidade e da deformação final obtidos através do software Instron Bluehill® com os valores calculados através da análise minuciosa dos dados provenientes dos instrumentos de medição (célula de carga, extensômetro, sensor de deslocamento). Busca-se, assim, fornecer informações que auxiliem o trabalho de técnicos e engenheiros, além de estimar o erro percentual e desenvolver uma metodologia periódica para a garantia da confiabilidade da máquina de ensaio.

Aug 7, 2018

By D Sert, A Jayasekara, P Gardin, B J Monaghan, S J. Chew, P Zulli, D Pinson, X F. Dong, R Ferreira

In an ironmaking blast furnace (BF), molten slag and hot metal form in the softening-melting (cohesive) zone and then trickle through the coke packed bed before being discharged from the taphole. During their downward flow, there are significant interactions occurring between liquids and other phases, such as gas and packing particles. Overall, the formation, dripping and discharging of these liquid phases, particularly molten slag, have a significant impact on BF operations in terms of furnace permeability, fuel consumption, process stability, product quality and ultimately, productivity. Hence, understanding the liquid flow behaviour in the BF lower zone is critical for designing optimal operations. In the current investigation, the flow behaviour of slag droplets was investigated at a mesoscopic level using a combined numerical and physical modelling approach. The interaction between slag and carbonaceous materials was studied using sessile drop wetting experiments, slag flow through a funnel and a high temperature packed bed and the Volume of Fluid (VOF) modelling technique. Molten slag flow and counter-current gas-slag flow in the packed bed was investigated in terms of superficial gas velocity, slag properties and packing structure. The gas-slag flow behaviour at a mesoscopic level was numerically visualised, with gas velocity gradually increased up to the flooding point. The strong interaction between gas and slag was uniquely identified, which can cause localised slag flooding as well as gas channelling. Detailed information concerning the effect on slag holdup distribution, residence time and flow patterns of wettability, slag properties and bed structure were obtained. The current investigation highlights the significant role of research at a mesoscopic level in understanding macroscopic slag flow behaviour. Gas channelling, which is a critical phenomenon in a packed bed with counter-current gas-slag flow, is predicted. It can be speculated that significant gas channelling in the BF can inevitably occur prior to operational limits being reached. In the BF process, the formation of permanent gas channelling and large slag rivulets should be avoided to maintain appropriate contact between phases and hence, furnace permeability.

Jun 19, 2024

By III Kimball

For many years, Arizona merely shadowed EPA's environ-mental regulation of mining operations and waste. During this period, Arizona generally assisted EPA in the implementation of federal programs and enacted environmental laws patterned closely after their federal counterparts. A growing public concern about protecting water quality, particularly groundwater quality, eventually caused the State to depart from this pattern.

Jan 1, 1989

By T. S. Reddy

Research and Development Centre for Iron and Steel (RDCIS) a unit of Steel Authority of India Limited (SAIL) is continuously engaged in reduction of energy consumption at SAIL plants by implementing innovative and new concepts. In this regard, continuous efforts are being made to recover waste heat in Sinter Plants. This paper discusses existing waste heat recovery measures taken and proposed measures planned in Sinter Plants. One such effort is on waste heat recovery from sinter coolers. Hot sinter is discharged to the crusher at the end of the sinter machine at a temperature of 500 to 800°C. Temperature of hot sinter is brought down to nearly 100°C in the sinter cooler with air-cooling. The air after cooling the sinter is generally discharged to the atmosphere at about 225 to 300°C. It is planned to recover heat from the hot air that is being released to atmosphere and heat the process water, which is being added at ambient temperature in mixing drum at Bhilai Steel Plant. The temperature of raw sinter mix will be raised by addition of this hot water, which will help in improving the productivity of sinter machine. It is estimated that Waste heat recovery to the tune of 1.5 to 2.0 Gcal/h is possible with reduction in CO2 emissions in the range of 4000 to 5000 ton/year. The novel approach that is being adopted is addition of hot water in mixing drum for higher sinter productivity for the first time in India. Keywords: waste heat recovery, sinter plant, hot water generation, emission reduction, CDM

Sep 1, 2012

Viable domestic mineral industries are essential to the economic health of the United States and the well-being of its citizens. The charts in this publication reflect developments significant to the Nation's mineral industries during 1975. Last year was a year of reduced activity for the Nation's mineral industries. Although the value of the country's total mineral output rose, for example, the overall production and use of many minerals fell. At the same time, the industry experienced lower profits and higher debt/equity ratios. These and other adverse effects on many segments of the Nation's mineral industries resulted from the overall decline in domestic and international economic activity.

Jan 1, 1976

By Pengfei Wang, Guorui Feng, Shufeng Zhang, Yuxia Guo, Tingye Qi, Dian Li

"Based on the geological conditions of the No. 10203 mining face of the Xinyang coal mine, a numerical model of the longwall backfilling face is built using the FLAC3D software to calculate the limit broken length of the key strata. Based on the deformation laws of the immediate roof, the backfilling parameters are determined. Furthermore, the movement laws of the overburden strata with different volume filling rates (0, 40, 60, 100, and 100%) and with different layout forms of the filling strip (under a volume filling rate of 60%) are analyzed. The results of the numerical modeling show that the stress of the two sides of the working face and the deformation of the overlying rock are gradually reduced with the increment of the volume filling ratio. In view of the deformation of the roof strata within the allowable range, a volume filling rate of 60% is selected to simulate and analyze the filling effect under different layout forms of the filling strip. The filling width, stress concentration area, and layout form of the filling strip are the key factors to control the movement of the overlying strata. In addition, the probability integral formula is used to calculate and predict the ground subsidence on the filling area, which confirmed that the backfilling mining method is fully applicable in the Xinyang coal mine. The results of this study provide a certain theoretical basis for the determination of the filling process in the field.INTRODUCTIONIn China and other coal producing countries, gob is managed using the caving, filling, supporting, and slowly sinking methods (Zhang, Zhou, and Zhang, 2009). With the continuing development of the concept of green coal mining (Guo, Deng, and Zou, 2004), the filling method, which is safe and environmentally friendly, has been widely used in the field. On one hand, this method could reduce waste rock and other waste discharge. On the other hand, it could effectively slow the surface subsidence. Recently, strip-filling mining mostly adapted the arrangement of the strip backfill with equal intervals and widths (Xie et al., 2004), but the reasonability of this arrangement should be discussed. To arrange the intervals and width of the strip-filling body reasonably, Feng et al. (2019) put forward the “constructional backfill mining (CBM)” concept. The CBM is a type of backfill mining with low backfill rate, strong structural stability, and good backfill effect. The targets of the CBM include the efficient usage of solid waste resources in mining areas to reduce the backfill cost, the improvement of backfill materials and backfill technologies to increase the backfill efficiency, and rational planning of backfill and mining scheme to reuse the underground mining space. The determination of proper width and intervals for the strip-filling body is the main content of the CBM. Strip-filling mining using cemented coal gangue backfilling is the main method to undertake overburden of the overlying strata and to slow down the surface deformation. It also plays an effective role in cost reduction (Xu et al., 2007). This study focuses on proper determination of the strip-filling body parameters according to actual geological conditions by a simulation. It provides an appropriate reference for backfill mining in the Xinyang coal mine."

Jan 1, 2019